WO2000061235A1

WO2000061235A1 - Method of and system for extinguishing fire in defined spaces

Info

Publication number: WO2000061235A1
Application number: PCT/FI2000/000273
Authority: WO
Inventors: Hannu Tirronen; Teuvo Paukku
Original assignee: Softonex Oy Ltd
Priority date: 1999-03-30
Filing date: 2000-03-30
Publication date: 2000-10-19
Also published as: FI990711A0; AU3821000A

Abstract

The invention relates to a method of extinguishing a fire started in a defined space by spraying a mist comprising of very small drops into said space. According to the invention the spraying is made at a point which is located in the wall (2) or in the immediate vicinity of the wall of the defined space (1) so that the spray is directed away from said wall (2, 32), and that at least a part of the spraying is directed to travel mainly in parallel with the ceiling of the defined space for cooling hot combustion gases accumulating in the upper part of the defined space. The invention relates also to a system for extinguishing a fire in the manner mentioned above.

Description

Method of and system for extinguishing fire in defined spaces

This invention relates to a method of extinguishing a fire started in a defined space, particularly in a ship's cabin or in a hotel room, by spraying a mist comprising of very small drops into said space. This invention relates also to a system for extinguishing a fire in different defined spaces having a ceiling, a floor and walls as well as a nozzle head fastened to a surface of the defined space, the nozzle head's nozzle house having an input opening connected to the supply pipe for fire extinguishing water and at least one nozzle opening for spraying the pressurised fire extinguishing water as small drops into the defined space. In this connection a defined space means also a space which is open on one or two, more seldom on more sides, but which regarding the fire extinguishing can be regarded as a defined space, i.e. a space where a started fire can be extinguished with the fire extinguishing equipment located in said space.

It is previously known to extinguish a fire started in defined spaces by spraying water into this space from nozzles arranged in its ceiling. In order to minimise water damages there has been used nozzles from which the water is sprayed as very small drops having a large evaporation area compared to the amount of water used. The object is then to displace air from the seat of fire and around it by the steam generated by the evaporation in order to extinguish the fire. At the same time an object is to cool the gases generated by the fire so that they do not later again catch fire when they are mixed with air containing oxygen, and to prevent the fire from spreading.

However, now it has been found that with the above-mentioned methods and systems it is not always possible to extinguish fires in a sufficiently effective manner, particularly when the fires were started in defined spaces, such as in ship cabins and hotel rooms. This is due to the fact that the drops sprayed from the nozzles located in the ceiling do not reach in a sufficiently effective way the shaded areas of the defined space, such as intermediate spaces in bunk beds, spaces below beds, tables and chairs etc. Then there is a risk that a fire started in such places can gain power so that it is not anymore possible to extinguish it, that the hot gases generated in the fire can flow into other spaces and start new seats of fire there, or that the seat of fire generates so much smoke that the situation becomes fatal.

A disadvantage of the nozzles located in the ceiling is further that if it is desired to hide the water pipes, there must be made holes for the nozzle heads in the ceiling panels, and often there must be made a plurality of these holes, one for each nozzle head, in order to create a sufficient effective area. Thus it is relatively cumbersome and also expensive to locate the nozzle heads in the ceiling.

Further, from the patent publication FI 101680 it is previously known to install a nozzle head on the wall of a defined space in order to prevent a fire occurring in the defined space from spreading outside the defined space. The patent publication presents equipment for preventing a fire, in which equipment at least one nozzle is located in the wall of the defined space, close to the door of the defined space in order to form a barrier at the door with the aid of the spray generated by high pressure, in order to prevent the fire and smoke generated by it from spreading. The problem of the equipment according to the above-mentioned publication regarding the extinguishing of a fire in a defined space is the high pressure used in the equipment which directs the water spray in a predetermined direction. Thus, there is often required separate additional nozzles mounted in the ceiling of the space in order to extinguish the actual fire. Thus the object of the present invention is to provide a method of and a system for extinguishing rapidly and reliably a fire started in a defined space, with a minimum amount of water and without having to make holes in the ceiling panels of the defined space.

The main characteristics of the invention become apparent in the enclosed claims.

Thus according to the present invention the spraying is not made from the ceiling as to this day, but from a point which is located on the wall or in the immediate vicinity of the wall of the defined space. In this connection "immediate vicinity of the wall" means a point which is located close to the wall, at a distance from it, but not in the ceiling.

Already in its initial phase a fire will generate gas flows in the defined space, when substituting air comes from the sides to the seat of fire and hot gases rise upwards. By directing a spray from the wall of the defined space at such a pressure that the pressure at the discharging point is below 16 bar, advantageously from the upper part of the wall e.g. obliquely downwards, the small droplets in the spray can be caused to be pulled into the substituting air flowing to the seat of fire, in which case the drops are effectively conveyed to the actual seat of fire, even if it would be concealed under a surface. Similarly the hot gases generated by the fire tend to flow upwards and along the ceiling to the sides, in which case a spray directed from the upper part of the wall meets these hot gases flowing along the ceiling and is mixed with them, cooling them effectively.

It is particularly advantageous to perform the spraying from a point which is above an opening in the wall of the defined space, and particularly advantageously above the doorway. Then the spray formed by droplets is aimed at the substituting air flow flowing through the doorway and substantially in parallel with the flow, whereby the droplets are effectively transported into the seat of fire, even if it would be concealed under a surface, such as under a bed or a table. In a similar way, in order to get out from the defined space the hot gases generated in the fire must meet the spray directed almost horizontally above the door- way, whereby the hot gases are effectively cooled, so that they do not catch fire again when they meet much oxygen containing air outside the defined space. In this way an explosive spreading of the fire can be prevented effectively.

The sprays are directed partly horizontally, or almost horizontally, i.e. parallel with the ceiling, and partly in an oblique angle in relation to the ceiling, and the spraying can be carried out simultaneously from several places, in which case the sprays form an angle between them. In this way the drops can be spread in the shape of a fan or a cone over a large area, so that a part of the drops are conveyed to the seat of fire and another part of the drops will cool the hot combustion gases generated in the fire before they exit the defined space. More than 20 %, typically about 40 to 60 % of the spray is directed to travel in an angle of 0 to 30 degrees in relation to the ceiling. Another part of the spray is directed to travel in an angle of about 30 to 80 degrees in relation to the ceiling.

On the average the drop size is preferably at most about 1 mm, in which case their area is sufficiently large compared to the amount of water used, in order to extinguish the fire effectively with small water damages. Water is advantageously used as the extinguishing medium. In ships it is also possible to spray sea water when all the fresh water in the piping has been used. Some medium known as such which increases the efficiency of the fire extinguishing can also be added to the water.

The fire extinguishing system according to the invention can also be constructed to be triggered automatically, so that there is a piston against the water input opening in the nozzle house, the piston rod extending from the nozzle house and outside the nozzle head. Then outside the nozzle head there is a supporting member for a triggering ampoule detecting the temperature, the ampoule being located between the outer end of the piston rod and a control member in the supporting member. The control member presses the triggering ampoule against the end of the piston rod, so that the piston will tightly close the input opening of the nozzle house. When the temperature rises the triggering ampoule is broken, in which case the water pressure pushes the piston away from the input opening, so that the water can flow through the nozzle house to the nozzles.

The present invention is particularly advantageous in ships, as there is no need to make openings in the cabins' ceiling panels for the nozzle heads, but the water pipes can be mounted along the inner side of the walls above the cabin door. As it is now possible according to the present invention to extinguish fires with a smaller amount of water than previously, we can get on with smaller pumps and a lower number of spare equipment than previously. With the method and system according to the invention fires can be extinguished in defined spaces with as small amounts of water as less than 3 litres per square metre.

The invention is described in more detail below with reference to the enclosed drawings, in which

Figure 1 shows in a cross section a ship's cabin provided with a system according to the invention;

Figure 2 shows in an exploded view a nozzle head according to the invention as seen from one side;

Figure 3 shows the same nozzle head seen from above and with the nozzles dis- mounted; Figure 4 shows in a cross section as seen from one side the nozzle head of figures 2 and 3 in an untriggered state;

Figure 5 shows the same nozzle head as in figure 4 when it has been triggered and water is sprayed from the nozzles; and

Figure 6 shows a defined space provided with a system according to the invention, as seen obliquely from above.

In figure 1 a defined space, in this case a ship cabin, is marked with the reference number 1, its ceiling with the reference number 3, the walls with the reference number 2, and the floor with the reference number 6. The door of the cabin 1 is marked with the reference number 5 and the bunk beds in the cabin are marked with the reference number 4. The flows of air and combustion gases are marked with arrows, and, as seen in figure 1, a fire has started between the beds 4. The nozzle head 10 extinguishing the fire is according to the invention arranged above the door 5 within the cabin 1.

As seen in figure 1, fresh substituting air flows from the lower part of the door 5 along the floor 6 to the seat of fire, and the combustion gases rising from the seat of fire flow along the ceiling 3 of the cabin 1 out from the cabin 1 through the upper part of the doorway 5.

Water is sprayed from the nozzle head 10 as very small drops which spread in the cabin 1 in the form of a cone or fan, in different directions from obliquely downwards to almost horizontally, in parallel with the ceiling 3. The drop sprays directed obliquely downwards meet the substituting air flowing along the floor 6 and are conveyed with this flow to the seat of fire where the drops evaporate, and the generated steam displaces oxygen and extinguishes effectively the seat of fire. On the other hand, the drops sprayed from the nozzle head 10 substantially in parallel with the ceiling 3 hit the combustion gases flowing in the opposite direction and mix effectively with the gases, whereby the temperature of the combustion gases drops, so that outside the cabin 1 they will not catch fire anymore, because their temperature has decreased so much.

The nozzle head used in the fire extinguishing system according to the invention is shown in more detail in figures 2 and 3. It can be seen that the nozzle head 10 is formed by a nipple 13 connecting to a water pipe, a piston 16 provided with a packing 22 and having a piston rod 17, a trigger ampoule 18, and a threaded control member 19, all of these arranged in succession on the same longitudinal axis. The nozzle head 10 has further a plurality of nozzle parts 15 arranged next to each other and on top of each other in the openings 21 and forming an angle between them, so that the nozzle head generates a conical water jet which comprises very small water drops, less than 1 mm.

The nozzle head 10 further has a nozzle house, which is closed by a cover 23, and at a distance from it an external supporting member 20, into which a control member 19 is screwed, so that the trigger ampoule 18 is pressed between the control member and the end of the piston rod projecting from the nozzle head.

The operation of the nozzle head 10 according to the invention is presented in more detail in figures 4 and 5. The body of the nozzle head 10 is generally marked with the reference number 1, and it has a nozzle house 12 closed by a cover 23, and for the connection to a water pipe the nozzle house has an opening for a nipple 13 which contains a seat 14 for a piston 16, which piston is pressed against the seat 14 in the rest position so that water flow to the nozzle house 12 is prevented. The rod 17 of the piston 16 extends across the nozzle house 12 through the body 11 and outside the body. A trigger ampoule 18 is located between the outer end of the piston rod 17 and the threaded control member 19 pro- vided in the supporting member 20 arranged in the body 11, which trigger ampoule 18 is pressed against the outer end of the piston rod 17 with the aid of the control member 19.

From the nozzle house 12 there are further openings 21 in different directions into which there are mounted nozzle parts 15, which openings thus form an angle between them, and the adjacent nozzle parts 15 are arranged in two rows on top of each other.

Figure 5 shows the situation after triggering the trigger ampoule. The trigger ampoule known as such is triggered when the temperature rises due to a fire, in which case the pressure prevailing in the water pipe forces the piston 16 away from the seat 14 of the nipple 13, whereby the water can flow into the nozzle house 12 and further to be sprayed from the nozzle parts 15 into the defined space.

Figure 6 shows an embodiment of the system according to the invention when it is installed in a large-sized defined space 31, whereby the height of the space 31 is marked with the reference X, the width is marked with the reference Z, and the length is marked with the reference Y. The defined space 31 can be for instance the turbine room in a power plant, or another corresponding space with a typical large volume with a height of for instance over five metres. In order to extinguish a fire started in the space 31 a plurality of nozzles 33 are mounted in the walls 32 of the space, as shown in the figure. The mutual distance between the nozzles 33 is determined according to the fire extinguishing effect of one nozzle. If it has been determined for instance in fire tests that the fire extinguishing effect of one nozzle is y' metres in the width direction, x' metres in the height direction, and z' metres in the length direction, then the nozzles are advantageously installed in the space 31, so that the distance between them will be y' metres in the width direc- tion, x' metres in the height direction, and z' metres in the length direction. In the case shown in the figure the effect of the nozzles 33 is z' metres in the length direction, which is half of the width Z of the space 31, in which case it suffices to install nozzles 33 on the opposite walls 32 to cover the whole width Z of the space 31. The nozzles 33 are installed at distances x' and y' from each other, as shown in the figure.

The extinguishing medium is supplied to the nozzles 33 with pipes 34, which are installed in the walls 32 outside the space 31. Holes for the nozzles 33 are drilled in the walls. Then, for instance when a fire extinguishing system is installed as retrofitting in a space where it is not possible to work long periods, for instance due to the heat in the space, the installation of the fire extinguishing system in a manner according to the invention is made possible without extra interruptions in the operation. The fire extinguishing system according to the invention is further easy to install even in close quarters in connection with reparation and modifica- tion work, as it is not necessary to install nozzles in the ceiling of the space, where it would be particularly cumbersome to install the piping conveying the fire extinguishing medium. The fire extinguishing medium can be fed to the piping 34 e.g. with a separate pump, with the aid of a pressurised reservoir, or by connecting the piping to form a part of another fire extinguishing system.

In the case shown in figure 6 all nozzles can be connected to the same piping and thus they can be simultaneously triggered automatically or manually. One or more smoke detectors, flame detectors, heat detectors or the like, can be arranged in the space 31 to be protected, so that the detector provides an alarm for the manual triggering or starts the fire extinguishing system automatically. The automatic triggering can start a fire extinguishing liquid pump or open a valve in order to pressurise the piping, so that the fire extinguishing liquid starts to discharge from all nozzles simultaneously. When a fire starts in the space 31 shown in figure 6, the nozzles 33 are triggered and they start to spray a low pressure mist-like spray into the space 31. The mist is sprayed into the space 31 in a quantity of about one litre per each volume cubic metre during about one minute. After the extinguishing operation the fire has usually been extinguished. When required, the mist-like spraying can be continued for further extinguishing the fire, or for cooling the surfaces. When a fire is extinguished according to the invention with the aid of only a small amount of the mist-like medium, there will not occur any rapid temperature changes in any hot objects, such as motors and the like possibly present in the space, which rapid changes could lead to a breakdown of the object.

It is obvious that the invention may be varied within very wide limits within the scope of the enclosed claims. Thus there may be more nozzle heads than one, and a nozzle head can also be located in the ceiling, as long as it is sufficiently close to a side wall, so that the water drops can be sprayed generally away from this wall. A nozzle head can also be located above another opening than the doorway, such as for instance above a vent or a window. When the window breaks due to the heat the drops sprayed from the nozzle house are pulled by the entering air to the seat of fire.

Claims

1. A method of extinguishing a fire started in a defined space (1 , 31) by spraying a mist comprising of very small drops into said space, characterised in that the spraying is made at a point which is located on the wall (2, 32) or in the im- mediate vicinity of the wall (2, 32) of the defined space (1, 31) so that the spray is directed away from said wall (2, 32), and that at least a part of the spraying is directed to travel mainly in parallel with the ceiling of the defined space for cooling hot combustion gases accumulating in the upper part of the defined space.

2. A method according to claim 1, characterised in that more than 20 %, typi- cally about 40 to 60 % of the spray is directed to travel in an angle of about 0 to

30 degrees in relation to the ceiling (3).

3. A method according to claim 2, characterised in that a second part of the spray is directed to travel in an angle of about 30 to 80 degrees in relation to the ceiling.

4. A method according to claim 1, characterised in that the spraying is made from a point which is in the upper part of said wall (2) of the defined space (1).

5. A method according to any previous claim, characterised in that the spraying is made from a point which is above an opening, preferably a doorway (5, 35) in the wall (2, 32) of the defined space (1, 31).

6. A method according to claim 5, characterised in that the spray is directed into the substituting air flow flowing from said opening and substantially in parallel with it in order to convey small drops into the seat of fire.

7. A method according to claim 1, characterised in that the spraying is made until the defined space (1, 31) is filled by a mist formed by small drops.

8. A method according to claim 1, characterised in that the fire extinguishing liquid is sprayed into the defined space (1, 31) in an amount which is about 0.5 to 2 litres per each volume cubic metre of the defined space.

9. A method according to claim 1, characterised in that the spraying is typically carried out for 30 seconds to 2 minutes, preferably for about one minute.

10. A method according to any previous claim, characterised in that the spraying is carried out with such a pressure that it in the discharge point of the spray is less than 16 bar.

11. A method according to any previous claim, characterised in that there is sprayed fresh water and/or sea water, to which there is possibly mixed any medium which makes the fire extinguishing more effective.

12. A method according to any previous claim, characterised in that there is sprayed drops having a drop size which on average is maximally about 1 mm.

13. A method according to any previous claim, characterised in that the spraying is simultaneously made from several points (15).

14. A system for extinguishing a fire in defined spaces (1) having a ceiling (3), a floor (6) and walls (3, 32) as well as a nozzle head (10) fastened to a surface of the defined space (1), the nozzle head having a nozzle house (12) with an input opening (14) connected to a feed pipe of fire extinguishing water and at least one nozzle opening (15) for spraying the pressurised fire extinguishing water as small drops into the defined space (1), characterised in that the nozzle head (10) is on the wall (2, 32) or in the immediate vicinity of the wall of the defined space (1) and directed so that it sprays the fire extinguishing water away from said wall (2, 32) and arranged so that it directs at least a part of the fire extinguishing water spray to travel mainly in parallel with the ceiling in order to cool the hot combus- tion gases accumulated in the upper part of the defined space.

15. A system according to claim 14, characterised in that the nozzle head (10) is in the upper part of the wall (2, 32) of the defined space (1, 31).

16. A system according to claim 14, characterised in that the at least one nozzle opening in the nozzle head (10) is directed so that more than 20 %, typically about 40 to 60 % of the fire extinguishing water spray discharged from the nozzle openings (15) in the nozzle head (10) is directed in an angle of about 0 to 30 degrees in relation to the ceiling (3) of the defined space (1).

17. A system according to claim 16, characterised in that at least one second nozzle opening (15) in the nozzle head (10) is directed obliquely downwards, so that the fire extinguishing water spray is discharged from them in an angle of about 30 to 60 degrees in relation to the ceiling.

18. A system according to any previous claim 14 to 17, characterised in that the nozzle head (10) is above an opening, preferably a doorway (5, 35) in the wall (2, 31) of the defined space (1, 31).

19. A system according to any previous claim 14 to 18, characterised in that the nozzle head (10) contains a plurality of nozzle openings (15) forming an angle between them and are located next to each other and/or on top of each other.

20. An automatically triggered system according to any previous claim 14 to

19. characterised in that there is a piston (16) against the input opening (14) of the nozzle house (12), the piston rod (17) of the piston extending from the nozzle house (12) outside the nozzle head (10), where there is a supporting member (20) for a trigger ampoule (18) detecting the temperature, the ampoule being located between the outer end of the piston rod (17) and a control member (19) in the supporting member (20), whereby the trigger ampoule (18) can be pressed against the end of the piston rod (17) with the aid of the control member (19), so that the piston (16) tightly closes the input opening (14) of the nozzle house (12).